Compositions and processes for treating subterranean formations

ABSTRACT

A gelling composition and a process for using the gellimg composition for oilfield applications are provided. The gelling composition comprises a water-soluble polymer, a crosslinking agent, and a liquid wherein the water-soluble polymer comprises repeat units derived from a nitrogen-containing olefinic monomer and optionally an olefinic comonomer. The gelling composition can be used in drilling fluids, workover fluids, completion fluids, permeability corrections, water or gas coning prevention, fluid loss prevention, matrix acidizing, fracture acidizing, and combinations of any two or more thereof.

This application is a division of application Ser. No. 08/575,434, filed Dec. 20, 1995, now allowed.

FIELD OF THE INVENTION

The present invention relates to compositions which can be used to prepare water-soluble polymers that are useful in oil field applications and processes for producing the compositions; to water-soluble polymers which can be prepared from the compositions and nitrogen-containing olefinic compounds as well as processes for producing and using the water-soluble polymers; and to gelling compositions produced from the water-soluble polymers for applications in a subterranean formation such as, for example, altering permeability and correcting water coning problems and processes for producing and using the gelling compositions.

BACKGROUND OF THE INVENTION

It is well known to those skilled in the art that polymers and gelled or crosslinked water-soluble polymers are useful in enhanced oil recovery and other oil field operations. They have been used to alter the permeability of underground formations in order to enhance the effectiveness of water flooding operations. Generally, polymers or polymers along with a gelling agent such as an appropriate crosslinking agent in a liquid are injected into the formation. The polymers then permeate into and gel, in the cases when a polymer and a crosslinking agent are used, in the regions having the highest water permeability.

Polymers have also been used in subterranean formation treatments such as "matrix acidizing" and "fracture acidizing". Because such treatments are well known to one skilled in the art, description of which is omitted herein and can be found in U.S. Pat. No. 4,997,582, description of which is herein incorporated by reference.

Because of environmental concerns as well as cost for disposing of a produced brine which is defined as the brine co-produced with oil and gas and is generally contaminated with some oil, or gas, or both, it is desirable to utilize the produced brine as the liquid used for the polymers and appropriate crosslinking systems. Use of produced brines eliminates not only the cost associated with acquiring and pre-treating fresh water for use as the liquid but also the disposal cost for the produced brine. Most produced brines are known to be hard brines, i.e., those having a divalent cation concentration greater than 1000 ppm.

Many polymers have been developed and used in processes for the recovery of hydrocarbons. Generally a desirable property is that such polymers impart to a liquid an increased viscosity when a relatively small quantity of the polymer is added, and preferably at a minimal cost. Another desirable property is that such polymers form gels, in the presence of a suitable gelling agent such as a crosslinking agent. However, a number of such polymers are not capable of forming gels having high thermal stability, i.e., the gels formed show high syneresis after a short period, such as for example a few days, at high temperature, such as for example, 120° C. in a harsh environment such as sea water.

Various polymers may be used in the process for recovery of hydrocarbons. For example, metallic ions crosslink gellable polymers through the interaction with the oxygen atoms of the polymer molecules. Therefore, the gellable polymers generally contain some carboxylate groups. Generally, the gellable polymers used such as, for example, polyacrylamide are of high molecular weight and contain high degrees of hydrolysis, i.e., contain 10-30 mole % carboxylate groups. However, these high molecular weight and/or high mole % carboxylate group-containing polymers gel almost instantly in the presence of the above-described multivalent metallic compounds. Such fast gelation rate renders the application of gelling compositions containing these polymers and multivalent metallic compounds not useful in many oil-field applications such as, for example, water shut-offs and permeability reductions.

Many processes have been developed to delay the gelation of gelling compositions by adding a gelation delaying agent to the gelling compositions. However, a gelation delaying agent is not inexpensive and a gelation delaying agent often adds appreciable costs to oil field operation. Furthermore, many gellable polymers cannot withstand a hostile environment as described above.

There is therefore an increasing demand for water-soluble polymers that can be used to prepare gels which withstand hostile environments. A hostile environment includes, but is not limited to, high temperatures, high salinity and/or high content of multivalent metal cations, commonly known as "hardness ions", as well as the high acidity, temperature and shear conditions encountered in processes such as acid fracturing.

In the art of drilling wells to tap subterranean deposits of natural resources, such as gas, geothermal steam or oil, it is well known to use a drilling fluid. In addition to having the desirably rheological properties such as viscosity and gel strength, it is very important that such drilling fluids exhibit a low rate of filtration or water loss, that is, the drilling fluid must prevent excessive amounts of fluid, or "filtrate", from flowing from the bore hole into the surrounding formation. The loss of water or other fluid from the drilling hole is prevented by the formation of a filter cake which deposits from the drilling fluid and seals the wall of the bore hole. Numerous formulations, compositions and additives to optimize the performance of drilling fluids for various applications have been developed. For instance, compositions comprising mixtures of carboxylic acid polymers and soluble metal salts with the object of increasing the "yield" (defined as the number of barrels of 15 centipoise mud which can be prepared from one ton of clay) of relatively low-grade clays have been used.

Excessive fluid loss from the drilling fluid may contaminate the producing formation, permanently displacing oil and blocking production. The adverse consequences of excessive fluid loss in the drilling of very deep wells are more severe due to the high temperatures and pressures encountered in such drilling operations. The viscosity of a fluid normally decreases with an increase in temperature, but certain polymer additive or deflocculating agents may reduce, or even reverse, this tendency. However, the polymers which are most effective in achieving this effect are the most vulnerably to breakdown through oxidation, shear and thermal effects, i.e., the duration of exposure to high temperature drilling operations. Also, many such polymers tend to precipitate and/or lose viscosity as well as effectiveness as water loss additives when exposed to dissolved electrolytes, particularly when divalent metal cations such as Ca⁺² and Mg⁺² are present. In drilling fluids, the resulting vulnerability to breakdown is exacerbated by the density of drilling mud, which is directly related to weighting agents required for a given formation pressure.

Breakdown of polymers causes a large increase in the fluid loss accompanied by an increase in filter cake thickness. These conditions often result in differential sticking of the drill string. It is, therefore, desirable to develop additives which enable drilling fluids to retain their proper viscosity and fluid content over a broader range of conditions.

Drilling fluids are used in the drilling of various types of wells. Workover and completion fluids, in contrast, are those fluids used in the completion and servicing of such wells. Completion fluids are those fluids used after drilling is complete and during the steps of completion, or recompletion, of the well. Completion can include cementing the casing, perforating the casing, setting the tubing and pump, etc.

Workover fluids are those fluids used during remedial work in the well. This can include removing tubing, replacing a pump, cleaning out sand or other deposits, logging, reperforating, etc. Workover also broadly includes steps used in preparing an existing well for secondary or tertiary oil recovery such as polymer additions, micellar flooding, steam injection, etc.

Both workover and completion fluids are used in part to control well pressure, to prevent the collapse of casing from overpressure, and to prevent or reduce corrosion of casing. A drilling fluid may be suitable for completion or workover applications in some cases, but not in all cases.

Although there has been considerable progress in the field of workover and completion fluids, there is significant room for further improvement. For example, wells are being completed and serviced in increasingly hostile environments involving, e.g., high temperatures and high levels of salinity and/or hardness in the formation water. Thus, new additives for workover and completion fluids which retain their properties at elevated temperatures and high concentrations of dissolved electrolytes are in demand.

Therefore, a composition which can be used to prepare a more hostile environment-withstanding polymer as well as a hostile environment-withstanding gelling composition, containing the hostile environment-withstanding polymer, that can form stable gels in a liquid such as, for example, produced brines, for near-wellbore as well as in-depth treatments, and preferably that does not require a gelation delaying agent, is highly desirable.

SUMMARY OF THE INVENTION

An object of the invention is to provide a composition which can be used as a monomer to synthesize a hostile environment-withstanding, water-soluble polymer. Another object of the invention is to provide a process for synthesizing the composition. Yet another object of the present invention is to provide a water-soluble polymer that can be used to form a gel in a hostile environment in hydrocarbon-bearing subterranean formations. Also an object of the invention is to provide a process for altering the permeability of hydrocarbon-bearing subterranean formations using the water-soluble polymer or for other drilling applications. A further object of the invention is to provide a gelling composition which contains the water-soluble polymer and withstands a hostile environment. Still another object of the present invention is to provide a process for various drilling applications or for altering the permeability of hydrocarbon-bearing subterranean formations by using a gelling composition that contains the water-soluble polymer, withstands hostile environment, and is environmentally suitable for use in subterranean formations. Still a further object of the invention is to provide a process for various drilling applications or for altering the permeability of hydrocarbon-bearing subterranean formations with a gelling composition that does not require a gelation delaying agent. Yet still another object of the invention is to provide a process for treatment of subterranean formations employing a gelling composition that is environmentally suitable for subterranean formation operations. An advantage of the invention is that the gelling compositions of the invention generally withstand a hostile environment and the processes generally do not employ a gelation delaying agent, yet achieve the alteration of permeability of the formations or can be used in other applications. Other objects, features, and advantages will become more apparent as the invention is more fully disclosed hereinbelow.

According to a first embodiment of the present invention, a composition that can be used to prepare a water-soluble polymer which can be used in a hydrocarbon-bearing subterranean formation is provided. The composition comprises a nitrogen-containing olefinic compound.

According to a second embodiment of the present invention, a process for preparing a composition is provided that can be used to prepare a water-soluble polymer which can be used in a hydrocarbon-bearing formation wherein said composition comprises a nitrogen-containing olefinic compound.

According to a third embodiment of the present invention, a water-soluble polymer which can be used in a hydrocarbon-bearing formation is provided. The polymer comprises repeat units derived from at least one nitrogen-containing olefinic compound.

According to a fourth embodiment of the present invention, a process which can be used for treating hydrocarbon-bearing formation is provided comprises introducing into the formation a water-soluble composition wherein the water-soluble composition comprises a water-soluble polymer comprising repeat units derived from at least one nitrogen-containing olefinic compound.

According to a fifth embodiment of the present invention, a gelling composition is provided which comprises a water-soluble polymer, a crosslinking agent, and a liquid wherein the water-soluble polymer comprises repeat units derived from at least one nitrogen-containing olefinic compound.

According to a sixth embodiment of the present invention, a process is provided which comprises introducing into a subterranean formation a gelling composition comprising a water-soluble polymer, a crosslinking agent, and a liquid wherein the gelling composition forms gels when introduced into the formation and the water-soluble polymer comprises repeat units derived from at least one nitrogen-containing olefinic compound.

DETAILED DESCRIPTION OF THE INVENTION

According to the first embodiment of the present invention, a composition useful as a monomer for synthesizing a water-soluble polymer is provided. The composition comprises, or consists essentially of, or consists of a nitrogen-containing olefinic compound having the formula selected from the group consisting of sulfobetaines, vinylic amides, and combinations of any two or more thereof wherein the sulfobetaine has the formula of R₁ C(R₁)═C(R₁)--(C═O)_(m) --(Ar)_(m) --Y--N⁺ (R₂) (R₂)--Y--SO₃ ⁻ and the vinylic amide has the formula of ##STR1## or combinations of any two or more thereof. R₁ and R₂ can be the same or different and are each independently selected from the group consisting of hydrogen, alkyl radicals, aryl radicals, aralkyl radicals, alkaryl radicals, and combinations of any two or more thereof wherein each radical can contain 1 to about 30, preferably 1 to abut 20, more preferably 1 to about 15, and most preferably 1 to 10 carbon atoms and can contain functional group(s) such as ammonium, hydroxyl, sulfate, ether, carbonyl groups, amine groups, sulfhydryl groups, or combinations of any two or more thereof which can contribute to water solubility of polymers produced therefrom. Preferably R₁ is hydrogen and R₂ is hydrogen, methyl, ethyl, or combinations of two or more thereof. Y is an alkylene radical, a phenylene group, an imidazolium group, a naphthylene group, a biphenylene group, or combinations of any two or more thereof. Each Y is preferably independently an alkylene radical which can have 1 to about 20, preferably 1 to about 15, and more preferably 1 to 10 carbon atoms. Most preferably, Y is a short alkylene radical having 1 to about 5 carbon atoms. Ar is an arylene radical, preferably a phenylene group, which can be substituted or unsubstituted. X is an anion selected from the group consisting of halides, sulfates, phosphates, nitrates, sulfonates, phosphonates, sulfinates, phosphinates, and combinations of any two or more thereof. Each m can be the same or different and is 0 or 1.

Examples of suitable nitrogen-containing olefinic compounds of the first embodiment of the invention include, but are not limited to, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N-acryloyl-N'-methyl-N'-(2-amino-2-oxoethyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(2-amino-2-oxoethyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinylimidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinylimidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinylimidazolium chloride, and combinations of any two or more thereof.

The nitrogen-containing olefinic compounds of the first embodiment of the invention can be prepared by the process disclosed hereinbelow in the second embodiment of the invention.

In the second embodiment of the present invention, a process for preparing the nitrogen-containing olefinic compounds is provided. The nitrogen-containing olefinic compounds having the formula of R₁ C(R₁)═C(R₁)--(C═O)_(m) --(NH)_(m) --(Ar)_(m) --Y--N⁺ (R₂) (R₂)--Y--SO₃ ⁻ (a sulfobetaine), can be produced by contacting a vinylic tertiary amine with an alkylating agent such as, for example, an alkylsulfonic acid containing a proper leaving group such as halide, hydroxyl, tosylate, other suitable leaving groups, or combinations of any two or more thereof. These reagents can be contacted, under any suitable conditions so long as the conditions can effect the production of the nitrogen-containing olefinic compounds, in a solvent such as toluene, benzene, pentane, hexane, acetonitrile, methanol, ethanol, any other common organic solvent or combinations of any two or more solvents. Generally, a tertiary amine can be contacted with an alkylating agent at a temperature in the range of from about 10° to about 120° C., preferably about 20° to about 90° C., and most preferably 35° to 65° C. for about 1 to about 10 days, preferably about 1 to about 8 days, and most preferably 1 to 5 days under any suitable pressures such as, for example, about 1 atmospheric pressure. A suitable radical inhibitor such as 1,3-dinitrobenzene cam be added to prevent polymerization of the nitrogen-containing olefinic compounds during the contacting. Preferably the production is carried out by using 1,3-propanesultone or 1,4-butanesultone as the alkylating reagent in toluene by heating at 45°-50° C. for 72 hours. The sulfobetaine generally precipitates from the solvent and can be purified by filtration, repeated washing with any common organic solvent that does not dissolve the sulfobetaine, and finally dried under reduced pressure. Preferably diethyl ether is used to wash the sulfobetaine during filtration, and the product can be dried under a pressure such as, for example, 5 cm Hg for 48 hours.

Examples of suitable tertiary amines include, but are not limited to, N,N-dimethyl-N-(4-vinylbenzyl) amine, N,N-dimethyl-N-(4-vinylbenzyl) amine, N,N-dipropyl-N-(4-vinylbenzyl) amine, N,N-diethyl-N-(2-vinylbenzyl) amine,N,N-dimethyl-N-(3-vinylbenzyl)amine, N,N-dimethyl-N-(3-vinylbenzyl) amine,N,N-dipropyl-N-(3-vinylbenzyl) amine, N,N-dimethyl-N-(2-vinylbenzyl) amine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-vinyl imidazole, and combinations of any two or more thereof.

Examples of suitable alkylating reagents include, but are not limited to, 3-chloro-propane-1-sulfonic acid, 4-chloro-butane-1-sulfonic acid, 3-hydroxy-propane-l-sulfonic acid, 4-hydroxy-butane-1-sulfonic acid, the corresponding esters of the hydroxy-alkane-1-sulfonic acids such as 1,3-propanesultone and 1,4-butanesultone, and combinations of any two or more thereof.

The nitrogen-containing olefinic compounds with the amide functional group of the first embodiment of the invention have general formulae of ##STR2## and combinations of any two or more thereof. These compounds can be produced by alkylation of a vinyl-substituted amine with an alkylating agent such as, for example, an alkyl amide containing a proper leaving group such as halide, hydroxyl, tosylate, other suitable leaving groups, or combinations of any two or more thereof. These reagents can be contacted, under any conditions so long as the conditions can effect the production of the nitrogen-containing olefinic compounds in a solvent such as toluene, benzene, pentane, hexane, acetonitrile, methanol, ethanol, any other common organic solvents, or combinations of any two or more thereof. Generally, a vinyl-substituted amine and an alkylating agent can be contacted under a condition including a temperature in the range of from about 10° to about 150° C., preferably about 20° to about 120° C., and most preferably 30° to 100° C. for about 1 to about 15 days, preferably 1 to 8 days under any suitable pressure such as, for example, about 1 atmospheric pressure. A suitable radical inhibitor such as, for example, 1,3-dinitrobenzene can be added to prevent polymerization of the nitrogen-containing olefinic compounds during the contacting. Preferably the production is carried out by using a 2-chloro-acetamide as the alkylating agent in acetonitrile by heating at 45°-80° C. for 50-150 hours. The nitrogen-containing olefinic compounds generally precipitate from the solvent and can be purified by filtration, repeated washing with any common organic solvent that does not dissolve the nitrogen-containing olefinic compounds, and finally dried under reduced pressure. Preferably diethyl ether is used to wash the nitrogen-containing olefinic compounds during filtration, and the nitrogen-containing olefinic compounds generally can be dried under a suitable pressure such as, for example, 5 cm Hg for 48 hours.

Examples of suitable vinyl-substituted amines include, but are not limited to, N,N-dimethyl-N-(4-vinylbenzyl) amine, N,N-dimethyl-N-(4-vinylbenzyl) amine, N,N-diethyl-N-(4-vinylbenzyl) amine, N,N-diethyl-N-(4-vinylbenzyl) amine, N,N-dimethyl-N-(3-vinylbenzyl) amine, N,N-dimethyl-N-(3-vinylbenzyl) amine, N,N-diethyl-N-(3-vinylbenzyl) amine, N,N-diethyl-N-(3-vinylbenzyl) amine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-vinyl imidazole, and combinations of any two or more thereof.

Examples of suitable alkylating agents include, but are not limited to, 2-chloro-acetamide, 2-bromo-acetamide, 3-chloro-propanamide and 3-bromo-propanamide, and combinations of any two or more thereof.

In the second embodiment of the invention, the molar ratio of the alkylating agent to the amine can be any ratio so long the ratio can effect the production of the nitrogen-containing olefinic compounds. Generally, the molar ratio can be in the range of from about 1:0.01 to about 0.01:1, preferably about 1:0.05 to about 0.05:1, and most preferably 1:0.1 to 0.1:1. The molar ratio of the radical inhibitor to the amine can be in the range of from about 0.1:1 to about 1,000:1. The molar ratio of the solvent to the amine can be any ratio that is effective in the production of a nitrogen-containing olefinic compound and can be in the range of from about 0.1:1 to about 1,000:1.

According to the third embodiment of the present invention, a water-soluble polymer is provided which can withstand a hostile environment and can be used for treating a hydrocarbon-bearing subterranean formation. The water-soluble polymer comprises, or consists essentially of, or consists of, repeat units derived from at least one nitrogen-containing olefinic compound. The term "polymer" as used herein denotes a molecule having at least about 10 repeat units and can be homopolymer, copolymer, terpolymer, tetrapolymer, or combination of any two or more thereof.

Any nitrogen-containing olefinic compounds having a polymerizable ethylenic linkage and being capable of producing a polymer which withstands hostile environment can be used for preparing the water-soluble polymer of the third embodiment of the present invention. Though it is not necessary, it is preferred that the ethylenic linkage be at the terminal end of the nitrogen-containing olefin molecule and that at least one nitrogen be a tertiary amine. The presently preferred repeat units include, but are not limited to ##STR3## and combinations of any two or more thereof. R₁ and R₂ can be the same or different and are each independently selected from the group consisting of hydrogen, alkyl radicals, aryl radicals, aralkyl radicals, alkaryl radicals, and combinations of any two or more thereof wherein each radical can contain 1 to about 30, preferably 1 to abut 20, more preferably 1 to about 15, and most preferably 1 to 10 carbon atoms and can contain functionalities such as, for example, hydroxyl, sulfate, carbonyl, amine, sulfhydryl, or combinations of any two or more thereof. Preferably R₁ is hydrogen, R₂ is hydrogen, methyl, ethyl, or combinations of any two or more thereof. M is a morpholine group which can be substituted or unsubstituted. Y is an alkylene radical, a phenyl group, an imidazolium group, a naphthyl group, a biphenyl group, or combinations of any two or more thereof which can have 1 to about 20, preferably 1 to about 15, and most preferably 1 to 10 carbon atoms. Most preferably, Y is a short alkylene radical having 1 to about 5 carbon atoms. Ar is an arylene radical, preferably phenyl, which can be substituted or unsubstituted. X is an anion selected from the group consisting of halides, sulfate, phosphate, nitrate, sulfonates, phosphonates, sulfinates, phosphinates, and combinations of any two or more thereof. Each m can be the same or different and is independently 0 or 1.

The water-soluble polymer of the third embodiment of the present invention can be a homopolymer, copolymer, terpolymer or tetrapolymer. However, if the nitrogen-containing olefinic repeat units contain an amide group, it is preferred that the water-soluble polymer be derived from repeat units comprising at least one of the nitrogen-containing olefinic compounds described above and at least one olefinic comonomer selected from the group consisting of R₁ --C(R₁)═C(R₁)--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --Z, R₁ --C(R₁)═C(R₁)--Y--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --N(R₂)--Y--R₂, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --G--Y--Z, R₁ C(R₁)═C(R₁)--(C═O)_(m) --O)_(m) --G--Y--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --O)_(m) --Y--Z, and combinations of any two or more thereof wherein Z has a formula selected from the group consisting of N(R₂)(R₂), N⁺ (R₂)(R₂)(R₂)X⁻, and combinations of any two or more thereof wherein X is an anion selected from the group consisting of halides, sulfate, phosphate, nitrate, sulfonates, phosphonates, sulfinates, phosphinates, and combinations of any two or more thereof. M, Y, R₁, and R₂ are the same as those disclosed above. The letter m is 0 or 1. G is N(R₁) or O. W is an acid moiety selected from the group consisting of phosphinic acid, phosphonic acid, sulfinic acid, sulfonic acid, sulfuric acid, sulfurous acid, carboxylic acid, phosphoric acid, ammonium salts or alkali metal salts of these acids, and combinations of any two or more thereof.

Examples of suitable nitrogen-containing olefinic compounds of the third embodiment of the invention include, but are not limited to, N-acryloyl morpholine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(3-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-ethyl piperazinium chloride, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinyl imidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinyl imidazolium chloride, N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propanammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propanammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propanammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propanammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethanammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethanammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethanammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethanammonium inner salt, and combinations of any two or more thereof.

Examples of suitable olefinic comonomers include, but are not limited to, acrylamide, styrene sulfonic acid, salt of styrene sulfonic acid, N-methylacrylamide, N,N-dimethylacrylamide, acrylic acid, salt of acrylic acid, N-vinylpyrrolidone, methyl acrylate, methacrylate, vinylic sulfonic acid, salt of vinylic sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, salt 2-acrylamido-2-methylpropanesulfonic acid, and combinations of any two or more thereof. The salt can be an ammonium salt, an alkali metal salt, or combinations of any two or more thereof.

Some of the olefinic comonomers can be purchased commercially. The others can be synthesized by the process disclosed in the second embodiment of the present invention or in the Examples section.

For example, the olefinic comonomers having the formula of R₁ --C(R₁)═C(R₁)--(C═O)_(m) --M in which M is the same as disclosed above can be prepared from R₁ --C(R₁)═C(R₁)--(C═O)_(m) --X where X is the same as that disclosed above, such as acryloyl chloride, and morpholine or from R₁ --C(R₁)═C(R₁)--(C═O)_(m) --OH, such as acrylic acid, and morpholine. The molar ratio of morpholine to the other reactant can be in the range of from about 2:1 to about 1:2. Generally, the reaction can be carried out in an organic solvent such as chloroform or any solvents illustrated above, at a temperature in the range of from about -50° C. to about 20° C., for about 1 to about 10 hours. The reactants are commercially available. See Examples section below for details.

The water-soluble polymers of the third embodiment of the present invention can be prepared by mixing the monomer(s) (i.e., the nitrogen-containing olefinic compounds and the olefinic comonomers), in desired molar ratios if copolymers, terpolymers, or tetrapolymers are desired, in an appropriate liquid medium and then initiating the free-radical polymerization in solution, suspension, or emulsion environment. Generally, any molar ratios can be employed depending on the final polymer desired. The liquid can be an aqueous solution, non-aqueous solution, or mixtures thereof.

Well known compounds commonly employed to initiate free radical polymerization reactions include hydrogen peroxide, azo compounds such as, for example, 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride, alkali metal persulfates such as K₂ S₂ O₈, alkali metal perborates, alkali metal perphosphates, and alkali metal percarbonates. Well known organic peroxide compounds commonly employed to initiate free radical polymerization reactions include lauryl peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-butylperoxyprivilate, t-butylperoctoate, p-methane hydroperoxide, and benzoylperoxide. The compound t-butylhyponitrite is a well known alkyl hyponitrite commonly employed to initiate free radical polymerization reactions. Furthermore, ultraviolet light and gamma radiation are commonly employed to initiate free radical polymerization reactions. In addition, such other method of polymerization as would have occurred to one skilled in the art may be employed, and the present invention is not limited to the particular method of preparing the polymer set out herein. Because the polymerization techniques are well known to one skilled in the art, the description of which is omitted herein for the interest of brevity.

If copolymers, terpolymers, or tetrapolymers are desired, the molar ratio of the nitrogen-containing olefinic monomer to the olefinic comonomer can be any ratio so long as the ratio can produce a polymer that can withstand hostile environment. Generally, the molar ratio can be in the range of from about 0.01:1 to about 100:1, preferably about 0.05:1 to about 50:1, and most preferably 0.1:1 to 30:1. If a combination of the nitrogen-containing olefinic monomers, or the olefinic comonomers, or both are employed, the molar ratios can be any ratio so long as the molar ratio of total nitrogen-containing olefinic monomers to the olefinic comonomers is within the range disclosed above.

According to the fourth embodiment of the present invention, a process which can be used in hydrocarbon-bearing subterranean formations such as water-flooding is provided. The process comprises, or consisting essentially of, or consisting of, introducing a water-soluble composition into a subterranean formation. The water-soluble composition comprises, consists essentially of, or consists of a water-soluble polymer. The scope of the water-soluble polymer is the same as that disclosed in the first embodiment of the present invention, description of which is omitted herein for the interest of brevity.

The term "process" used herein and hereinafter in conjunction with a subterranean formation generally denotes, unless otherwise indicated, a use in drilling fluids, workover fluids, completion fluids, permeability corrections, water or gas coning prevention, fluid loss prevention, matrix acidizing, fracture acidizing, and combinations of any two or more thereof.

The water-soluble composition used in the fourth embodiment of the invention can also comprise a liquid. The term "liquid" used in the present invention denotes water, a solution, a suspension, or combinations thereof wherein the suspension contains dissolved, partially dissolved, or undissolved substances such as salts. The presently preferred liquid is an aqueous liquid such as, for example, sea water or a produced brine which is defined above.

Examples of salts include metal salts. Generally, the total salts content can vary widely from, for instance, 1 to as high as 30 weight percent (%). The typical salts content can be in the range of from, for instance, about 2 to about 25 weight %.

The introduction of the water-soluble composition into a subterranean formation can be carried out by any methods known to one skilled in the art. Generally the water-soluble polymer can be dissolved, or substantially dissolved, in a liquid so that the water-soluble composition is present in the liquid in an amount, or concentration, sufficient to alter the permeability of a subterranean formation. The amount, or concentration, can be in the range of from about 50 to about 100,000, preferably about 100 to about 50,000, most preferably 200 to 10,000 mg of the water-soluble composition per liter of the liquid.

The water-soluble composition in a liquid medium can then be introduced, by any means known to one skilled in the art such as pumping, into a subterranean formation so that it can diffuse into the more water-swept portions of the formation. The nature of the formation is not critical to carrying out the process of the present invention. The formation can have a temperature in the range of from about 70° F. to about 400° F., preferably 75° F. to 350° F.

According to the fifth embodiment of the present invention, a gelling composition which can be used in oil field applications is provided. The gelling composition comprises, consists essentially of, or consists of a water-soluble composition, a crosslinking agent, and a liquid. The scope of the water-soluble composition is the same as that disclosed in the third embodiment of the present invention. The liquid component is the same as that disclosed in the fourth embodiment of the present invention.

Any crosslinking agents can be used. For example, a multivalent metallic compound that are capable of crosslinking the gellable carboxylate-containing polymer in the hydrocarbon-bearing formations can be used in the process of the present invention. Examples of suitable multivalent metal compounds include, but are not limited to, Al⁺³, Cr⁺³, Fe⁺³, Zr⁺⁴, Ti⁺⁴, and combinations of any two or more thereof.

The presently preferred multivalent metal compound is a metal compound selected from the group consisting of a complexed zirconium compound, a complexed titanium compound, and combinations of any two or more thereof. Examples of the preferred multivalent metallic compounds include, but are not limited to, zirconium citrate, zirconium complex of hydroxyethyl glycine, ammonium zirconium fluoride, zirconium 2-ethylhexanoate, zirconium acetate, zirconium neodecanoate, zirconium acetylacetonate, tetrakis(triethanolamine)zirconate, zirconium carbonate, ammonium zirconium carbonate, zirconyl ammonium carbonate, zirconium lactate, titanium acetylacetonate, titanium ethylacetoacetate, titanium citrate, titanium triethanolamine, ammonium titanium lactate, aluminum citrate, chromium citrate, chromium acetate, chromium propionate, chromium malonate, and combinations thereof. The presently most preferred crosslinking agent is zirconium lactate, zirconium citrate, tetrakis(triethanolamine)zirconate, or zirconium complex of hydroxyethyl glycine, or combinations thereof. These compounds are commercially available.

According to the fifth embodiment of the present invention, a metallic compound used as a crosslinking agent can also contain a complexing ligand if necessary to further delay the rate of gelation. Preferably, however, the crosslinking agent does not contain such complexing agent. The complexing ligand useful for the present invention to retard the rate of gelation is generally a carboxylic acid containing one or more hydroxyl groups and salts thereof. The complexing ligand can also be an amine that has more than one fuctional group and contains one or more hydroxyl groups and that can chelate the zirconium or titanium moiety of the zirconium or titanium compounds described above. Examples of suitable complexing ligands include, but are not limited to, hydroxyethyl glycine, lactic acid, ammonium lactate, sodium lactate, potassium lactate, citric acid, ammonium, potassium or sodium citrate, isocitric acid, ammonium, potassium or sodium isocitrate, malic acid, ammonium, potassium or sodium malate, tartaric acid, ammonium, potassium or sodium tartrate, triethanolamine, malonic acid, ammonium, potassium or sodium malonate, and mixtures thereof. The presently preferred complexing ligands are citric acid, lactic acid, tartaric acid and salts thereof, triethanolamine, and hydroxyethyl glycine because of their ready availability and low cost.

A crosslinking agent can also contain two components. The first crosslinking component useful as crosslinking agent is generally water-dispersible or soluble and can be phenol, substituted phenols, aspirin, p-aminobenzoic acid, resorcinol, catechol, hydroquinone, furfuryl alcohol, R'ArO (C═O)_(m) R', HOAr (C═O)_(m) OR', HOArOH, R'OArOH, R'OArOR', or combinations of any two or more thereof where Ar is an arylene group which can be non-substituted or substituted; each R' can be the same or different and is each independently selected from the group consisting of hydrogen, carboxylic group, a C₁ -C₆ alkyl, a phenyl group or combinations of any two or more thereof, and m is 0 or 1. The term "water dispersible" used herein is to describe a component that is truly water soluble or is dispersible in water to form a stable suspension. Examples of suitable first crosslinking components include, but are not limited to, phenol, hydroquinone, resorcinol, catechol, p-aminosalicylic acid, furfuryl alcohol, phenyl acetate, phenyl propionate, phenyl butyrate, salicylic acid, phenyl salicylate, aspirin, p-hydroxybenzoic acid, methyl p-hydroxybenzoate, methyl o-hydroxybenzoate, ethyl p-hydroxybenzoate, o-hydroxybenzoic acid, hexyl p-hydroxybenzoate, and combinations of any two or more thereof. Presently preferred water dispersible first crosslinking components are phenol, phenyl acetate, phenyl salicylate, methylp-hydroxybenzoate, resorcinol, catechol, hydroquinone, and combinations of any two or more thereof.

Any water-dispersible or soluble aldehyde, its derivative, or compound that can be converted into aldehyde can be utilized as the second crosslinking component in crosslinking agent. Examples of suitable second crosslinking components include, but are not limited to aliphatic monoaldehydes, aromatic monoaldehydes, aliphatic dialdehydes, aromatic dialdehydes, and their precursors. Preferred aldehydes and their precursors can be selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, decanal, glutaraldehyde, terephthaldehyde, hexamethylenetetramine, and combinations of any two or more thereof.

The weight ratio of the water-dispersible first crosslinking component to the second crosslinking component can be any ratio so long as the ratio can effect the gelation of the gelling composition. Generally, such ratio can be in the range of from about 0.01:1 to about 100:1, preferably about 0.1:1 to about 10:1, and most preferably 0.5:1 to 2:1.

Any suitable procedures for preparing the gelling composition can be used. Some of the polymers can require particular mixing conditions, such as slow addition of finely powdered polymer into a vortex of stirred brine, alcohol prewetting, protection from air (oxygen), preparation of stock solutions from fresh rather than salt water, as is known for such polymers.

The concentration or amount of the water-soluble polymer in the gelling composition can range widely and be as suitable and convenient for the various polymers, and for the degree of gelation needed for particular reservoirs. Generally, the concentration of the water-soluble polymer in a liquid is made up to a convenient strength of about 100 to 100,000 mg/l (ppm), preferably about 200 to 70,000 ppm, and most preferably 500 to 50,000 ppm.

The concentration of crosslinking agent used in the present invention depends largely on the concentrations of polymer in the composition. Lower concentrations of polymer, e.g., require lower concentrations of the crosslinking agent. Further, it has been found that for a given concentration of polymer, increasing the concentration of crosslinking agent generally substantially increases the rate of gelation. The concentration of crosslinking agent in the injected slug varies generally over the broad range of about 1 mg/l (ppm) to about 10,000 ppm, preferably over the range of about 1 ppm to about 7,500 ppm, and most preferably 1 ppm to 2,500 ppm. The liquid generally makes up the rest of the gelling composition.

The concentration of the complexing ligand, if present, in the gelling composition also depends on the concentrations of the water-soluble polymer in the composition and on the desired rate of gelation. Generally, the lower the concentration of the complexing ligand is, the faster the gelation rate is.

According to the sixth embodiment of the present invention, a process which can be used to alter the permeability of a subterranean formation is provided. The process comprises, or consists essentially of, or consists of introducing a gelling composition into a subterranean formation. The scope of the gelling composition is the same as that disclosed in the fifth embodiment of the invention.

The use of gelled polymers to alter the water permeability of underground formations is well known to those skilled in the art. Generally, an aqueous solution containing the polymer and a crosslinker is pumped into the formation so that the solution can enter into the more water swept portions of the formation and alter water permeability by gelling therein.

According to the process of the sixth embodiment of the present invention, an aqueous gelling composition comprising a crosslinking agent and a gellable polymer is injected into an injection or production well. The definition and scope of the crosslinking agent and gellable polymer are the same as those described above. The amount of the aqueous gelling composition introduced or injected can vary widely depending on the treatment volume injected. The amount of the gellable polymer injected is also dependent on the gel strength desired, same as that described for the crosslinking agent.

According to the sixth embodiment of the invention, the gelling can be prepared on the surface followed by introducing the prepared composition into a subterranean formation. Alternatively, individual components of the gelling composition described above can also be simultaneously or sequentially introduced into a subterranean formation.

The nature of the underground formation treated is not critical to the practice of the present invention. The described gelling composition can be introduced or injected into a formation having a temperature range of from about 70° F. to about 350° F. Any means known to one skilled in the art such as, for example, a pump means can be used for introducing or injecting the gelling composition and polymer solution.

Examples provided hereinbelow are intended to assist one skilled in the art to further understand the invention and should not be considered limitative.

EXAMPLE I

This example illustrates the preparation of nitrogen-containing olefinic monomers.

N-acryloyl morpholine (NAM) ##STR4##

N-acryloyl morpholine was prepared from morpholine and acryloyl chloride. Morpholine (0.35 mole; 30.0 g), 0.42 mole (42.5 g) of triethylamine and 0.1 g of 1,3-dinitrobenzene were dissolved in 350 ml of chloroform and cooled to ca.-15° C. Acryloyl chloride (0.42 mole; 37.8 g) was then added from a dropping funnel in such a way that the temperature in the reaction flask did not exceed 0° C. The reaction mixture was then allowed to reach room temperature (about 25° C.). After 2 hours at room temperature the solution was poured into an excess of diethyl ether (500 ml), and the precipitated material was filtered from the ether. The organic phase was concentrated on a rotavapour. Hydroquinone (0.1 g) was added to the crude product in order to prevent polymerization and then distilled under reduced pressure. The product was immediately placed in the refrigerator. B.p. 74° C./0.01 mbar. The yield was 64%.

N-acryloyl-N'-methyl piperazine (AMP) ##STR5##

N-acryloyl-N'-methyl piperazine was prepared by adding 0.44 mole (39.8 g) of acryloyl chloride to a solution of 0.40 mole (40.0 g) N-methyl piperazine and 0.1 g hydroquinone in 200 ml of acetonitrile. The addition was carried out in such a way that the temperature in the reaction flask did not exceed 5° C. The reaction mixture was allowed to reach room temperature. A 10M aqueous NaOH-solution (17.6 g NaOH in 44 ml distilled water, 0.44 mole) was then added and the precipitated material was filtered. The two phases were separated and the organic layer was dried with CaCl₂. Distillation under reduced pressure gave the product as a clear liquid. B.p. 90°-95° C./0.5 mbar. The yield was 72%.

N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt (AMPPS) ##STR6##

N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt was prepared from 0.26 mole (40.1 g) of N-acryloyl-N'-methyl piperazine and 0.29 mole (34.9 g) of 1,3-propanesultone. The reagents were mixed together with 0.1 g of 1,3-dinitrobenzene in 260 ml of acetonitrile. The reaction mixture was heated to 90° C. for 21/2hours. The precipitated material was then filtered and washed three times with diethyl ether (100 ml) each. The white powder was dried under reduced pressure (12 mm Hg) for 18 hours. The yield was 68%.

N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride (AOMPC) ##STR7## N-acryloyl-N'-methyl piperazine (0.13 mole; 20.0 g) was dissolved in 260 ml of dry acetonitrile (distilled over P₂ O₅) together with 0.1 g 1,3-dinitrobenzene. Then 0.16 mole (14.6 g) 2-chloro acetamide was added to the N-acryloyl-N'-methyl piperazine, and the mixture was heated to ca. 80° C. for 123 hours. A white, precipitated powder was filtered and washed three times with diethyl ether (150 ml). The product was dried under reduced pressure (12 mm Hg) for 12 hours. The yield was 75%.

N,N-dimethyl-N-(3-sulfopropvl)-N-(4-vinylbenzyl) ammonium inner salt (DMAMSPS) ##STR8##

N,N-dimethyl-N-(4-vinylbenzyl) amine (93.0 mmole; 15 g), 111.6 mmole (13.6 g) of 1,3-propanesultone and 0.1 g of 1,3-dinitrobenzene were mixed together and dissolved in 180 ml of toluene. The mixture was heated at 45°-50° C. for 72 hours. A white, precipitated material was filtered, washed three times with diethyl ether (100 ml), and finally dried under reduced pressure (11 mm Hg) for 15 hours. The yield was 87%.

N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride (AODVAC) ##STR9##

N,N-dimethyl-N-(4-vinylbenzyl) amine (62.0 mmole; 10.0 g), 68.0 mmole (6.4 g) of 2-chloro acetamide and 0.1 g of 1,3-dinitrobenzene were dissolved in 125 ml of acetonitrile and heated at ca. 45° C. for 48 hours. The precipitated material was filtered and washed three times with diethyl ether (100 ml). A white powder was dried under reduced pressure (12 mm Hg) for 16 hours. The yield was 88%.

N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride (AOVC) ##STR10##

1-Vinyl imidazole (0.17 mole; 15.8 g), 0.20 mole (19.1 g) of 2-chloro acetamide and 0.1 g of 1,3-dinitrobenzene were mixed together, dissolved in 340 ml of acetonitrile and heated at 70°-75° C. for three nights (about 64 hours). The precipitated material was then filtered and washed three times with acetonitrile (150 ml). The product was dried under reduced pressure (12 mm Hg) for 15 hours. The product was a white powder, and the yield was 65%.

N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propanammonium inner salt (APDAPS) ##STR11##

Acryloylchloride (0.70 mole; 63.8 g) and 0.1 g of hydroquinone were dissolved in 350 ml of acetonitrile and cooled to -15° C. Then 0.59 mole (60.0 g) of 3-dimethylamino-1-propylamine was added from a dropping funnel in such a way that the temperature in the reaction flask did not exceed 5° C. The reaction mixture was allowed to reach room temperature. A 10M aqueous NaOH-solution (28.0 g NaOH in 70 ml distilled water, 0.70 mole) was added and the precipitated material was filtered. The filtrate was concentrated on a rotavapour and then distilled under reduced pressure. B.p.122° C./0.1 mbar. The yield was 55%.

Eighty-three mmole (13.0 g) of this product was reacted further with 99.6 mmole (12.2 g) of 1,3-propanesultone in 83 ml of toluene. In the mean time, 0.1 g 1,3-dinitrobenzene was added to prevent polymerization. The reaction mixture was heated at ca. 55° C. for 3 hours. A white, precipitated powder was filtered and washed three times with diethyl ether (200 ml). Finally the product was dried under reduced pressure (12 mm Hg) for 17 hours. The yield was 80%.

EXAMPLE II

This example illustrates the production of polymers of the present invention.

Polymerizations were carried out in distilled water or synthetic sea water. For synthetic sea water, one liter distilled water contained 23.83 g NaCl, 0.21 g NaHCO₃, 10.77 g MgCl₂.6H₂ O, 1.65 g CaCl₂.2H₂ O, and 42.9 g anhydrous Na₂ SO₄. The monomer solution was 35 weight % and the initiator concentration was 0.3 mole % with respect to total concentration of monomers. The azo-type initiator VA-044 (2,2'-azobis(N,N'-dimethyleneisobutyramidine)dihydrochloride) was used to 1 5 start the polymerizations. The polymerizations were carried out at room temperature. In a typical synthesis, specified quantities of the monomers were dissolved in distilled water or synthetic sea water and the mixture was purged with nitrogen for 50 minutes. Initiator was then added. The polymers were precipitated in methanol or acetone, redissolved in distilled water or synthetic sea water and finally lyophilized. The term "parts" used hereinafter in defining a polymer denotes mole %. The products were white, amorphous powders.

Copolymer Am/AMP

Eighty parts of acrylamide and 20 parts of N-acryloyl-N'-methyl piperazine (AMP) were polymerized in distilled water for 4 hours with use of 0.3 mole % VA-044 as a initiator. The polymer was precipitated in acetone. The yield was 34%.

Copolymer Am/NAM

Eighty parts of acrylamide and 20 parts of N-acryloyl morpholine (NAM) were dissolved in distilled water and the polymerization was carried out with use of 0.3 mol % VA-044 as initiator. The polymerization was stopped after 6 hours. The polymer was precipitated in acetone. The yield was 69%.

Terpolymer Am/NAM/AMP

The polymer was prepared from 70 parts of acrylamide, 15 parts of N-acryloyl morpholine (NAM) and 15 parts of N-acryloyl-N'-methyl piperazine (AMP) with use of 0.3 mole % VA-044 as initiator. Distilled water was used as solvent. After 5 hours the polymer was precipitated in acetone. The yield as 41%.

Copolymer Am/AMPPS

Eighty parts of acrylamide and 20 parts of N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt (AMPPS) were polymerized in synthetic sea water for 2 hours with use of 0.3 mole % VA-044 as initiator. The polymer was precipitated in methanol. The yield was 62%.

Copolymer Am/DMAMSPS

A polymer was prepared from 80 parts of acrylamide and 20 parts of N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt (DMAMSPS) dissolved in synthetic sea water. 0.3 mole % VA-044 was used as initiator. After 4 hours the polymer was precipitated in methanol. The yield was 48%.

Copolymer Am/APDAPS

Eighty parts of acrylamide and 20 parts of N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloylamino)-1-propanammonium inner salt (APDAPS) were polymerized in synthetic sea water for 5 hours with use of 0.3 mole % VA-044 as initiator. The polymer was precipitated in methanol. The yield was 81%.

Terpolymer Am/AMP/DMAMSPS

Sixty parts of acrylamide, 20 parts of N-acryloyl-N'-methyl piperazine (AMP) and 20 parts of N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt (DMAMSPS) were dissolved in synthetic sea water and the polymerization was carried out with use of 0.3 mole % VA-044 as initiator.

The polymerization was stopped after 31/2hours by precipitation of the polymer in methanol. The yield was 23%.

Terpolymer Am/AMP/APDAPS

Seventy parts of acrylamide, 25 parts of N-acryloyl-N'-methyl piperazine (AMP) and 5 parts of N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloylamino)-1-propanammonium inner salt (APDAPS) were polymerized in synthetic sea water with use of 0.3 mole % VA-044 as initiator. The polymerization was stopped after 3 hours by precipitation of the polymer in methanol. The yield was 59%.

Terpolymer Am/AMP/AMPPS

Seventy parts of acrylamide, 15 parts of N-acryloyl-N'-methyl piperazine (AMP) and 15 parts of N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt (AMPPS) were dissolved in synthetic sea water and polymerized for 23 hours. VA-044 was used as initiator. The polymer was precipitated in methanol. The yield was 34%.

Copolymer AOMPC/AMPS

Fifty parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 50 parts N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride (AOMPC) and 50 parts NaOH were dissolved in NaCl-solution and polymerized for 6 hours with use of 0.3 mole % VA-044 as initiator. The polymer was precipitated in methanol. The yield was 54%.

Terpolymer AOVC/AMP/AMPS

A polymer was prepared from 15 parts of N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride (AOVC), 70 parts of N-acryloyl-N'-methyl piperazine (AMP), 15 parts of 2-acrylamido-2-methylpropane-sulfonic acid (AMPS) and 15 parts of NaOH in synthetic sea water. Three tenths mole % VA-044 was used as initiator and the polymerization was stopped after 5 hours by precipitation of the polymer in methanol. The yield was 38%.

AOMPC Homopolymer.

N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride (AOMPC) (20.19 mmol) was dissolved in synthetic sea water and 0.3 mole % VA-044 was added. The polymerization was stopped after 6 hours by precipitation of the polymer in acetone. The yield was 57%.

Terpolymer Am/AMP/AMPS

Seventy parts of acrylamide, 15 parts of N-acryloyl-N'-methyl piperazine (AMP) and 15 parts of 2-acrylamido-2-methyl-propanesulfonic acid (AMPS) were dissolved in distilled water and polymerized for 3 hours. Three tenths mole % VA-044 was used as initiator. The polymer was precipitated in acetone. The yield was 47%.

EXAMPLE III

This example illustrates the preparation of gelling compositions from the polymers disclosed above and the stability of gels formed from the gelling compositions.

Preparation of Gelling Compositions

Stock solutions of a polymer contained 4 weight % of the polymer in synthetic sea water. The polymer solution was allowed to stand at least three nights (about 64 hours) with magnetic stirring before use.

Stock solutions of phenol, formaldehyde and HMTA each containing 10,000 mg/l (ppm) were used.

For each test 4.0 g of gelling composition were made by adding polymer, phenol and formaldehyde/HMTA solution and diluting with synthetic sea water to the correct concentration. The same ppm concentration of both phenol and formaldehyde/HMTA was used. Magnetic stirring was used to mix the gelling compositions. After mixing the pH of the gelling compositions were registered using pH indicator strips. The pH of the of the gelling composition was not adjusted in any way. The gelling compositions were thereafter transferred to glass vials, and the solutions were flushed with argon gas for 5 minutes before the vials were closed. The glass vials were weighed before and after adding gelling compositions.

For aging at 120° C., the glass vials were placed in stainless steel containers filled with water. After aging at 120° C., the stainless steel containers were cooled down to room temperature, the gel strength of the samples were characterized visually as weak, strong or rigid. The syneresis of the gels were measured as (weight of gel after exposure)/(initial weight of gel forming solution).

For gels in ampules, the syneresis was measured by measuring the gel height and the length of the liquid layer after aging.

Measurement of Inherent Viscosity

Polymer solution (0.1 weight %) in synthetic sea water was made for viscosity measurements. The polymer solution was allowed to stand for 3 days with magnetic stirring. Before viscosity measurement the polymer solution was filtered through a 5 υm Millipore filter. The relative viscosity of the 0.1 weight % polymer solution (relative to synthetic sea water) was measured with an Ubbelhode viscosimeter with an inner capillary diameter of 0.69 mm. At least 3 parallel measurements were performed for each solution. The temperature of the polymer solution under the viscosity measurement was 25.0±0.05° C.

Relative viscosity: =time for polymer solution through capillary/time for synthetic sea water trough capillary

Inherent viscosity: ln(rel. visc.)/0.1 g/dl

The results of viscosity measurements of polymers and gel properties of gelling copositions made from these polymers are shown in the following Tables I-XXI. These tables show that gels formed from the polymers of the present invention were resistant to high temperature and high salinity environment. These Tables also show that little or no syneresis was observed after prolonged aging at high temperature and high salinity environment.

                                      TABLE I     __________________________________________________________________________                  Polymer                       Phenol/                           Gel height (G)        Am/AMP.sup.a             Inherent                  conc.                       HMTA.sup.d                           and Liquid height (L) after aging     Run        Feed Viscosity                  (ppm) in                       (ppm of                           at 120° C. in SNSW for     No.        Ratio.sup.b             dl/g SNSW.sup.c                       each)                           30 days                                 55 days                                       70 days     __________________________________________________________________________     181        80/20             5.4   6200                       2500                           G = 25 mm                                 G = 25 mm                                       G = 25     JSI                   L - 5 mm                                 L = 5 mm                                       L = 5 mm     II 23                 Rigid Rigid Rigid     181        80/20             5.4  10400                       2500                           G = 30 mm                                 G = 25 mm                                       G = 25 mm     JSI                   L = 0 mm                                 L = 5 mm                                       L = 5 mm     II 23                 Rigid Rigid Rigid     181        80/20             5.4  20000                       2500                           G = 26 mm                                 G - 24 mm                                       G = 24 mm     JSI                   L = 0 mm                                 L = 1 mm                                       L = 2 mm     II 23                 Rigid Rigid Rigid     __________________________________________________________________________      .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine

                  TABLE II     ______________________________________                             Polymer                                    Phenol/                    Inherent conc.  HMTA.sup.d                                           Weight % gel.sup.e     Run  Am/AMP.sup.a                    Viscosity                             (ppm) in                                    (ppm of                                           Gel Character     No.  Feed Ratio.sup.b                    dl/g     SNSW.sup.c                                    each)  5 months     ______________________________________     181  80/20     5.4       6200  2500   80     HSI                                   Rigid     II 23     181  80/20     5.4      10400  2500   80     JSI                                   Rigid     II 23     181  80/20     5.4      20000  2500   90     JSI                                   Rigid     II 23     ______________________________________      .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE III     ______________________________________                             Polymer                                    Phenol/           Am/AMP.sup.a                    Inherent conc.  HCHO.sup.d                                          Weight % gel.sup.e     Run   Feed     Viscosity                             (ppm) in                                    (ppm of                                          Gel Character     No.   Ratio.sup.b                    dl/g     SNSW.sup.c                                    each) 5 days                                                30 days     ______________________________________     154   70/30    5.1      20000  2500        100     TOB                                        Strong     VII 43     168   70/30    3.8      10000   500         55     JSI                                        Weak     I 76     168   70/30    3.8      20000  2500        100     JSI                                        Rigid     I 76     155   60/40    4.3      20000  2500        100     TOB                                        Strong     VII 52     155   60/40    4.3       5000  1000   82     TOB                                  Rigid     VII 52     155   60/40    4.3      10000  1000  100     TOB                                  Strong     VII 52     155   60/40    4.3      10000  2000  100     TOB                                  Rigid     VII 52     156   50:50    3.4      20000  2500        100     TOB                                        Weak     VII 49     156   50/50    3.5       5000  1000   83     TOB                                  Strong     VII 49     156   50/50    3.5      10000  1000   89     TOB                                  Strong     VII 49     156   50/50    3.5      10000  2500  100     TOB                                  Rigid     VII 49     ______________________________________      .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HCHO = formaldehyde      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE IV     ______________________________________                             Polymer           Am/AMP.sup.a                    Inherent conc.  Phenol.sup.d /                                           Weight % gel.sup.f     Run   Feed     Viscosity                             (ppm) in                                    HMTA.sup.e                                           Gel Character     No.   Ratio.sup.b                    dl/g     SNSW.sup.c                                    (ppm)  30 days     ______________________________________     154   70/30    5.1      10000  2000   96     TOB                                   Strong     VII 43     154   70/30    5.1      20000  2000   100     TOB                                   Strong     VII 43     168   70:30    3.8       5000  1000   61     JSI                                   Strong     I 76     168   70:30    3.8      10000   500   73     JSI                                   Weak     I 76     168   70:30    3.8      10000  1000   80     JSI                                   Weak     I 76     155   60/40    4.3      10000  2000   92     TOB                                   Weak     VII 52     155   60/40    4.3      20000  2000   100     TOB                                   Strong     VII 52     197   60/40    3.8      20000  2500   100     JSI                                   Rigid     II 63     197   60/40    3.8      10000  2500   90     JSI                                   Rigid     II 63     198   60/40    3.7      20000  2500   100     JSI                                   Rigid     II 65     156   50/50    3.5      20000  2000   100     TOB                                   Weak     VII 49     ______________________________________      .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d 2500 ppm      .sup.e HMTA = hexamethylenetetramine      .sup.f Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                                      TABLE V     __________________________________________________________________________        Am/       Polymer                       Phenol/                           Gel height (G)        NAM.sup.a             Inherent                  conc.                       HMTA.sup.d                           and Liquid height (L) after aging     Run        Feed Viscosity                  (ppm) in                       (ppm of                           at 120° C. in SNSW for     No.        Ratio.sup.b             dl/g SNSW.sup.c                       each)                           30 days                                 55 days                                       70 days     __________________________________________________________________________     179        80:20             4.4   5400                       2500                           G = 30 mm                                 G = 28 mm                                       G = 28 mm     JSI                   L = 5 mm                                 L = 7 mm                                       L = 7 mm     II 11                 Rigid Rigid Rigid     179        80:20             4.4  10300                       2400                           G - 27 mm                                 G = 27 mm                                       G = 27 mm     JSI                   L = 5 mm                                 L = 5 mm                                       L = 5 mm     II 11                 Rigid Rigid Rigid     179        80:20             4.4  20000                       2400                           G = 26 mm                                 G = 34 mm                                       G = 24 mm     JSI                   L = 3 mm                                 L = 5 mm                                       L = 5 mm     II 11                 Rigid Rigid Rigid     __________________________________________________________________________      .sup.a Am = acrylamide, NAM = Nacryloyl morpholine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine

                  TABLE VI     ______________________________________                             Polymer                                    Phenol/                    Inherent conc.  HMTA.sup.d                                           Weight % gel.sup.e     Run  Am/NAM.sup.a                    Viscosity                             (ppm) in                                    (ppm of                                           Gel Character     No.  Feed Ratio.sup.b                    dl/g     SNSW.sup.c                                    each)  5 months     ______________________________________     179  80/20     4.4       5400  2500   0.8     JSI                                   Rigid     II 11     179  80/20     4.4      10300  2400   0.9     JSI                                   Rigid     II 11     179  80/20     4.4      20000  2400   0.9     JSI                                   Rigid     II 11     ______________________________________      .sup.a Am = acrylamide, NAM = Nacryloyl morpholine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE VII     ______________________________________           Am/               Polymer                                    Phenol/           NAM.sup.a                    Inherent conc.  HCHO.sup.d     Run   Feed     Viscosity                             (ppm) in                                    (ppm of                                          Weight % gel.sup.e     No.   Ratio.sup.b                    dl/g     SNSW.sup.c                                    each) Gel Character     ______________________________________     170   80/20    6.2      10000   500        30     JSI                                        Strong     I 79     170   80/20    6.2      10000  2500        28     JSI                                        Strong     I 79     171   70/30    3.7      10000  1000  100     JSI                                  Rigid     I 81     172   60/40    3.3      20000  1000   92     JSI                                  Rigid     I 83      71   20/80    2.5      20000  2500  100   70     TOB                                  Strong                                                Strong     V 85     125   20/80    1.1      30000  4000   42   35     TOB                                  Strong                                                Strong     VII 17     125   20/80    1.1      30000  2000        55     TOB                                        Strong     VII 17     ______________________________________      .sup.a Am = acrylamide, NAM = Nacryloyl morpholine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HCHO = formaldehyde      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE VIII     ______________________________________          Am/     Inherent                          Polymer       Weight % gel.sup.f          NAM.sup.a                  Vis-    conc.  Phenol.sup.d /                                        Gel Character     Run  Feed    cosity  (ppm) in                                 HMTA.sup.c                                        30 days     No.  Ratio.sup.b                  dl/g    SNSW.sup.c                                 (ppm)  Parallel 1                                               Parallel 2     ______________________________________     150  70/30    2.2     20000  2000  93     94     JSI                                Rigid  Weak     I 59     150  70/30    2.2     10000  2000  100     JSI                                Rigid     I 59     151  60/40    2.2     20000  2000  96     80     JSI                                Rigid  Weak     I 61     152  50/50    2.5     20000  2000  90     100     JSI                                Strong Weak     I 63     ______________________________________      .sup.a Am = acrylamide, NAM = Nacryloyl morpholine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d 2500 ppm      .sup.e HMTA = hexamethylenetetramine      .sup.f Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE IX     ______________________________________           Am/NAM/            Polymer                                     Phenol/           AMP.sup.a Inherent conc.  HMTA.sup.d                                           Weight % gel.sup.e     Run   Feed      Viscosity                              (ppm) in                                     (ppm of                                           Gel Character     No.   Ratio.sup.b                     dl/g     SNSW.sup.c                                     each) 30 days     ______________________________________     188   70/15/15  4.6      10000  2500  100     JSI                                   Rigid     II 21     188   70/15/15  4.6      20000  2500  95     JSI                                   Rigid     II 21     188   70/15/15  4.6      10000  1000  47     JSI                                   Strong     II 21     ______________________________________      .sup.a Am = acrylamide, NAM = Nacryloyl morpholine, AMP =      Nacryloyl-Nmethyl piperazine      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE X     ______________________________________           Am/               Polymer                                    Phenol/           AMPPS.sup.a                    Inherent conc.  HCHO.sup.d                                          Weight % gel.sup.e     Run   Feed     Viscosity                             (ppm) in                                    (ppm of                                          Gel Character     No.   Ratio.sup.b                    dl/g     SNSW.sup.c                                    each) 5 days                                                30 days     ______________________________________     162   80/20    2.2      10000  2500  100     JSI                                  Strong     I 65     162   80/20    2.2      20000  1000  100     JSI                                  Rigid     I 65     162   80/20    2.2      10000  2000  100     JSI                                  Rigid     I 65     132   80/20    1.8      30000  4000  100   41     JSI                                  Rigid Strong     I 28     132   70/30    1.8      30000  2000        32     JSI                                        Strong     I 28     130   60/40    1.6      30000  4000  100   62     JSI                                  Strong                                                Strong     I 26     130   60/40    1.6      30000  2000        75     JSI                                        Strong     I 26     100   50/50             20000  2500   94   60     TOB                                  Weak  Weak     VI 68     120   50/40    1.5      30000  4000  100   88     TOB                                  Strong                                                Strong     VII 15     120   50/50    1.5      30000  2000        77     TOB                                        Strong     VII 15     ______________________________________      .sup.a Am = acrylamide, AMPPS = Nacryloyl-N(3-sulfopropyl)-Nmethyl      piperazinium inner salt      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HCHO = formaldehyde      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XI     ______________________________________                             Polymer                                    Phenol/                    Inherent conc.  HMTA.sup.d                                           Weight % gel.sup.e     Run  Am/AMPPS.sup.a                    Viscosity                             (ppm) in                                    (ppm of                                           Gel Character     No.  Feed Ratio.sup.b                    dl/g     SNSW.sup.c                                    each)  30 days     ______________________________________     202  80/20     3.5      10000  2500   Rigid     JSI                                   90     II 67     202  80/20     3.5      20000  2500   Rigid     JSI                                   70     II 67     ______________________________________      .sup.a Am = acrylamide, AMPPS = Nacryloyl-N(3-sulfopropyl)-Nmethyl      piperazine inner salt      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XII     ______________________________________                     Inherent                             Polymer                                    Phenol/           Am/       Vis-    conc.  HCHO.sup.d                                          Weight % gel.sup.e     Run   DMAMSPS.sup.a                     cosity  (ppm) in                                    (ppm of                                          Gel Character     No.   Feed Ratio.sup.b                     dl/g    SNSW.sup.c                                    each) 5 days                                                30 days     ______________________________________     149   90/10     1.0     10000  2500        81     JSI                                        Strong     I 55     149   90/10     1.0     20000  2500        88     JSI                                        Strong     I 55      65   80/20     0.9     10000  2500  100   79     TOB                                  Weak  Weak     V 79     137   80/20     2.0     30000  4000   93   72     TOB                                  Strong                                                Strong     VII 23     137   80/20     2.0     10000  1000   77     TOB                                  Strong     VII 23     137   80/20     2.0     10000  2500  100     TOB                                  Rigid     VII 23     ______________________________________      .sup.a Am = acrylamide, DMAMSPS =      N,Ndimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl)-ammonium inner salt      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HCHO = formaldehyde      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XIII     ______________________________________                              Polymer                                     Phenol/           Am/       Inherent conc.  HMTA.sup.d                                           Weight % gel.sup.e     Run   DMAMSPS.sup.a                     Viscosity                              (ppm) in                                     (ppm of                                           Gel Character     No.   Feed Ratio.sup.b                     dl/g     SNSW.sup.c                                     each) 30 days     ______________________________________     137   80/20     2.0      10000  2000  81     TOB                                   Weak gel     VII 23     137   80/20     2.0      20000  2000  100     TOB                                   Weak     VII 23     ______________________________________      .sup.a Am = acrylamide, DMAMSPS =      N,Ndimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl)-ammonium inner salt      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XIV     ______________________________________                              Polymer                                     Phenol/           Am/       Inherent conc.  HMTA.sup.d                                           Weight % gel.sup.e     Run   APDAPS.sup.a                     Viscosity                              (ppm) in                                     (ppm of                                           Gel Character     No.   Feed Ratio.sup.b                     dl/g     SNSW.sup.c                                     each) 30 days     ______________________________________     193   80/20     5.3       5000  2500  80     TOB                                   Rigid     VII 89     193   80/20     5.3      10000  2500  80     TOB                                   Rigid     VII 89     193   80/20     5.3      20000  2500  90     TOB                                   Strong     VII 89     ______________________________________      .sup.a Am = acrylamide, APDAPS =      N,Ndimethyl-N-(3-sulfopropyl)-3-(acryloylamino)-1-propanammonium inner      salt      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XV     ______________________________________                             Polymer           Weight %                     Inherent                             conc. Phenol/                                         Phenol/                                               gel.sup.f           Am/AMP/   Vis-    (ppm) HCHO.sup.d                                         HMTA.sup.c                                               Gel     Run   DMAMSPS.sup.a                     cosity  in    (ppm of                                         (ppm of                                               Character     No.   Feed Ratio.sup.b                     dl/g    SNSW.sup.c                                   each) each) 30 days     ______________________________________     195   60/20/20  2.4     10000 2500        100     TOB                                       Strong     VII 87     195   60/20/20  2.4     20000 2500        100     TOB                                       Rigid     VII 87     195   60/20/20  2.4     20000       2500  100     TOB                                       Rigid     VII 87     ______________________________________      .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine, DMAMSPS =      N,Ndimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl)-ammonium inner salt      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HCHO = formaldehyde      .sup.e HMTA = hexamethylenetetramine      .sup.f Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XVI     ______________________________________                              Polymer                                     Phenol/           Am/AMP/   Inherent conc.  HMTA.sup.d                                           Weight % gel.sup.e     Run   APDAPS.sup.a                     Viscosity                              (ppm) in                                     (ppm of                                           Gel Character     No.   Feed Ratio.sup.b                     dl/g     SNSW.sup.c                                     each) 30 days     ______________________________________     196   70/25/5   4.4       5000  2500  100     TOB                                   Rigid     VII 85     196   70/25/5   4.4      10000  2500  83     TOB                                   Rigid     VII 85     196   70/25/5   4.4      20000  2500  86     TOB                                   Rigid     VII 85     203   60/30/10  3.5      10000  2500  85     IBV                                   Rigid     I 49     203   60/30/10  3.5      20000  2500  85     IBV                                   Rigid     I 49     ______________________________________      .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine, APDAPS =      N,Ndimethyl-N-(3-sulfopropyl)-3-(acryloylamino)-1-propanammonium inner      salt      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XVII     ______________________________________           Am/AMP/           Polymer                                    Phenol/           APDAPS.sup.a                    Inherent conc.  HMTA.sup.d                                           Weight % gel.sup.e     Run   Feed     Viscosity                             (ppm) in                                    (ppm of                                           Gel Character     No.   Ratio.sup.b                    dl/g     SNSW.sup.c                                    each)  30 days     ______________________________________     184   70/15/15 1.9      10000  2500   70     JSI                                   Rigid     II 25     184   70/15/15 1.9      20000  2500   100     JSI                                   Rigid     II 25     ______________________________________      .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine, AMPPS =      Nacryloyl-N(3-sulfopropyl)-Nmethyl piperazinium inner salt      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HMTA = hexamethylenetetramine      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE VIII     ______________________________________           AOMPC/            Polymer                                    Phenol/           AMPS.sup.a                    Inherent conc.  HCHO.sup.d                                           Weight % gel.sup.e     Run   Feed     Viscosity                             (ppm) in                                    (ppm of                                           Gel Character     No.   Ratio.sup.b                    dl/g     SNSW.sup.c                                    each)  30 days     ______________________________________     189   50/50    1.1      10000  2500   100     IBV                                   Strong     I 43     ______________________________________      .sup.a AOMPC = Nacryloyl-N(2-amino-2-oxoethyl)-Nmethyl piperazinium      chloride, AMPS = 2acrylamido-2-methyl-propanesulfonic acid      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HCHO = formaldehyde      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XI     ______________________________________                              Polymer                                     Phenol/          AOVC/AMP/  Inherent conc.  HCHO.sup.d                                           Weight % gel.sup.e     Run  AMPS.sup.a Viscosity                              (ppm) in                                     (ppm of                                           Gel Character     No.  Feed Ratio.sup.b                     dl/g     SNSW.sup.c                                     each) 30 days     ______________________________________     191  15/70/15   1.6      20000  2500  100     JSI                                   Rigid     II 33     ______________________________________      .sup.a AOVC = N(2-amino-2-oxoethyl)-Nvinyl imidazolium chloride, AMP =      Nacryloyl-Nmethyl piperazine, AMPS = 2acrylamido-2-methyl-propanesulfonic      acid      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water      .sup.d HCHO = formaldehyde      .sup.e Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XX     ______________________________________                    Inherent  Polymer                                     Phenol/                    Viscosity conc.  HCHO.sup.c                                           Weight % gel.sup.d     Run   AOMPC    dl/g      (ppm) in                                     (ppm of                                           Gel Character     No.   Homopol.sup.a                    0.1 weight %                              SNSW.sup.b                                     each) 30 days     ______________________________________     117            1.4       30000  4000  100     TOB                                   Strong     VII 8     ______________________________________      .sup.a AOMPC = Nacryloyl-N(2-amino-2-oxoethyl)-Nmethyl piperazinium      chloride, homopolymer      .sup.b SNSW = synthetic sea water      .sup.c HCHO = formaldehyde      .sup.d Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

                  TABLE XXI     ______________________________________           Am/AMP/           Polymer                                    Phenol/           AMPS.sup.a                    Inherent conc.  HCHO.sup.d                                           Weight % gel.sup.e     Run   Feed     Viscosity                             (ppm) in                                    (ppm of                                           Gel Character     No.   Ratio.sup.b                    dl/g     SNSW.sup.c                                    each)  30 days     ______________________________________     157   50/25/25 3.4      20000  1000   100     TOB                                   Strong     VII 57     157   50/25/25 3.4      20000  2500   100     TOB                                   Strong     VII 57     ______________________________________      .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine, AMPS = 2 =      acrylamido2-methyl-propanesulfonic acid      .sup.b mole % ratio of monomers in the aqueous solution      .sup.c SNSW = synthetic sea water.      .sup.d HCHO = formaldehyde      .sup.c Weight % gel of initial weight of the solution after aging at      120° C. in synthetic sea water

EXAMPLE IV

This example is a comparative example showing that gels formed from a commonly employed polyacrylamide do not withstand well under a hostile environment condition as compared to the gels formed from the invention polymers.

A 7000 ppm solution of Dowell J333 polyacrylamide in seawater was crosslinked with phenol and formaldehyde at 120° C. Table XXII shows a summary of the results.

                  TABLE XXII     ______________________________________              Phenol/     Gel Height (G) and Liquid Height (L)     Polymer  Formaldehyde                          after 6 days aging at 120° C.     Concentration              (ppm of each)                          G (mm)   L (mm)     ______________________________________     7000      500        22       65      Rigid     7000     1000        20       70      Rigid     7000     2000        30       75      Rigid     ______________________________________

The results shown in Table XXII indicate that much syneresis occurred in gels formed from polyacrylamide only after aging for 6 days.

The results shown in the above examples clearly demonstrate that the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those inherent therein. While modifications may be made by those skilled in the art, such modifications are encompassed within the spirit of the present invention as defined by the disclosure and the claims. 

That which is claimed:
 1. A process comprising introducing into a subterranean formation a gelling composition which comprises a water-soluble polymer, a crosslinking agent, and a liquid whereinsaid polymer comprises repeat units derived from a nitrogen-containing olefinic monomer having the formula selected from the group consisting of ##STR12## and combinations of any two or more thereof; said crosslinking agent is selected from the group consisting of multivalent metal compounds, a two-component system, and combinations of any two or more thereof wherein the first component of said two-component system is selected from the group consisting of phenol, substituted phenols, aspirin, p-aminobenzoic acid, resorcinol, catechol, hydroquinone, furfuryl alcohol, R'ArO (C═O)_(m) R', HOAr (C═O)_(m) OR', HOArOH, R'OArOH, R'OArOR', or combinations of any two or more thereof and the second component of said two-component system is selected from aldehydes, derivatives of aldehydes, aldehyde precursors, and combinations of any two or more thereof; R¹, R₁, and R₂ are the same or different and are each independently selected from the group consisting of hydrogen, alkyl radical, aryl radical, aralkyl radical, alkaryl radical, and combinations of any two or more thereof wherein each radical contains 1 to about 30 carbon atoms; M is a substituted or unsubstituted morpholine group; each Y is independently selected from the group consisting of alkylene radical, phenylene group, imidazolium group, naphthylene group, biphenylene group, and combinations of any two or more thereof; Ar is an arylene group; and each m is independently 0 or
 1. 2. A process according to claim 1 wherein said polymer comprises repeat units derived from at least one olefinic comonomer having the formula selected from the group consisting of R₁ --C(R₁)═C(R₁)--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --Z, R₁ --C(R₁)═C(R₁)--Y--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --N(R₂)--Y--R₂, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --G--Y--Z, R₁ C(R₁)═C(R₁)--(C═O)_(m) --G--Y--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --Y--Z, and combinations of any two or more thereof whereinR₁ and R₂ are each independently selected from the group consisting of hydrogen, alkyl radical, aryl radical, aralkyl radical, alkaryl radical, and combinations of any two or more thereof; each m is independently 0 or 1; Z has the formula selected from the group consisting of N(R₂)(R₂), N⁺ (R₂)(R₂)(R₂)X⁻, and combinations thereof in which X is an anion selected from the group consisting of halide, sulfate, phosphate, nitrate, sulfonate, phosphonates, sulfinate, phosphinate, and combinations of any two or more thereof; G is N(R₂) or O; each Y is independently selected from the group consisting of alkylene radical, phenylene group, imidazolium group, naphthylene group, biphenylene group, and combinations of two or more thereof; and W is an acid moiety selected from the group consisting of phosphinic acid, phosphonic acid, sulfinic acid, sulfonic acid, sulfuric acid, sulfurous acid, carboxylic acid, phosphoric acid, ammonium salt or alkali metal salt of any of these acids, and combinations of any two or more thereof.
 3. A process according to claim 1 whereinsaid polymer comprises repeat units derived from at least one olefinic comonomer having the formula selected from the group consisting of R₁ --C(R₁)═C(R₁)--(C═O)_(m) --Z, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --Y--W, R₁ --C(R₁)═C(R₁)--W, R₁ --C(R₁)═C(R₁)--(C═O)--G--Y--W, and combinations of any two or more thereof; each R₁ is the same or different and is independently selected from the group consisting of hydrogen, alkyl radical, aryl radical, aralkyl radical, alkaryl radical, and combinations of any two or more thereof; each m is independently 0 or 1; Z has the formula selected from the group consisting of N(R₂)(R₂), N⁺ (R₂)(R₂)(R₂)X⁻, and combinatins thereof in which X is an anion selected from the group consisting of halide, sulfate, phosphate, nitrate, sulfonate, phosphonates, sulfinate, phosphinate, and combinations of any two or more thereof; G is N(R₁) or O; each Y is independently selected from the group consisting of alkylene radical, phenylene group, imidazolium group, naphthylene group, biphenylene group, and combinations of two or more thereof; and W is an acid moiety selected from the group consisting of phosphinic acid, phosphonic acid, sulfinic acid, sulfonic acid, sulfuric acid, sulfurous acid, carboxylic acid, phosphoric acid, ammonium salt or alkali metal salt of any of these acids, and combinations of any two or more thereof.
 4. A process according to claim 1 wherein said nitrogen-containing olefinic monomer is selected from the group consisting of N-acryloyl morpholine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(3-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-(thyl piperazinium chloride, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinyl imidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinyl imidazolium chloride, N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propane ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propane ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propane ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propane ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethane ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethane ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethane ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethane ammonium inner salt, and combinations of any two or more thereof.
 5. A process according to claim 1 wherein said nitrogen-containing olefinic monomer is selected from the group consisting of N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N-acryloyl-N'-methyl-N'-(2-amino-2-oxoethyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(2-amino-2-oxoelthyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinylimidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinylimidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinylimidazolium chloride, and combinations of any two or more thereof.
 6. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is selected from the group consisting of N-acryloyl morpholine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(3-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-ethyl piperazinium chloride, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinyl imidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinyl imidazolium chloride, N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-2-(acrylol amino)-1-ethaneammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, and combinations of any two or more thereof.
 7. A process according to claim 3 wherein said nitrogen-containing olefinic monomer has the formula selected from the group consisting of N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N-acryloyl-N'-methyl-N'-(2-amino-2-oxoethyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(2-amino-2-oxoethyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinylimidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinylimidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinylimidazolium chloride, and combinations of any two or more thereof.
 8. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is N-acryloyl-N'-methyl piperazine.
 9. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt.
 10. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride.
 11. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt.
 12. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride.
 13. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride.
 14. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propaneammonium inner salt.
 15. A process according to claim 3 wherein said nitrogen-containing olefinic monomer is N-acryloylmorpholine.
 16. A process according to claim 3 wherein said olefinic comonomer is selected from the group consisting of acrylamide, styrene sulfonic acid, salt of styrene sulfonic acid, N-methylacrylamide, N,N-dimcthylacrylamide, acrylic acid, salt of acrylic acid, N-vinylpyrrolidone, methyl acrylate, methacrylate, vinyl sulfonic acid, salt of vinyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, salt of 2-acrylamido-2-methylpropanesulfonic acid, and combinations of any two or more thereof.
 17. A process according to claim 3 wherein said olefinic comonomer is acrylamide.
 18. A process according to claim 1 wherein said crosslinking agent is a multivalent metal compound wherein the metal of said metal compound is selected from the group consisting of Al, Cr, Fe, Ti, and combinations of any two or more thereof.
 19. A process according to claim 1 wherein said crosslinking agent is selected from the group consisting of a zirconium compound, a titanium compound, a chromium compound, an aluminum compound, and combinations of any two or more thereof.
 20. A process according to claim 1 wherein said crosslinking agent is selected from the group consisting of zirconium citrate, zirconium complex of hydroxyethyl glycine, ammonium zirconium fluoride, zirconium 2-ethylhexanoate, zirconium acetate, zirconium neodecanoate, zirconium acetylacetonate, tetrakis(triethanolamine)zirconate, zirconium carbonate, ammonium zirconium carbonate, zirconyl ammonium carbonate, zirconium lactate, titanium acetylacetonate, titanium ethylacetoacetate, titanium citrate, titanium triethanolamine, ammonium titanium lactate, aluminum citrate, chromium citrate, chromium acetate, chromium propionate, chromium malonate, and combinations of any two or more thereof.
 21. A process according to claim 2 wherein said crosslinking agent is selected from the group consisting of zirconium citrate, zirconium complex of hydroxyethyl glycine, ammonium zirconium fluoride, zirconium 2-ethylhexanoate, zirconium acetate, zirconium neodecanoate, zirconium acetylacetonate, tetrakis(triethanolamine)zirconate, zirconium carbonate, ammonium zirconium carbonate, zirconyl ammonium carbonate, zirconium lactate, titanium acetylacetonate, titanium ethylacetoacetate, titanium citrate, titanium triethanolamine, ammonium titanium lactate, aluminum citrate, chromium citrate, chromium acetate, chromium propionate, chromium malonate, and combinations of any two or more thereof.
 22. A process according to claim 7 wherein said crosslinking agent is selected from the group consisting of zirconium citrate, zirconium complex of hydroxyethyl glycine, ammonium zirconium fluoride, zirconium 2-ethylhexanoate, zirconium acetate, zirconium neodecanoate, zirconium acetylacetonate, tetrakis(triethanolamine)zirconate, zirconium carbonate, ammonium zirconium carbonate, zirconyl ammonium carbonate, zirconium lactate, titanium acetylacetonate, titanium ethylacetoacetate, titanium citrate, titanium triethanolamine, ammonium titanium lactate, aluminum citrate, chromium citrate, chromium acetate, chromium propionate, chromium malonate, and combinations of any two or more thereof.
 23. A process according to claim 1 wherein said crosslinking agent comprises two components in which the first component is selected from the group consisting of phenol, hydroquinone, resorcinol, catechol, p-aminosalicylic acid, furfuryl alcohol, phenyl acetate, phenyl propionate, phenyl butyrate, salicylic acid, phenyl salicylate, aspirin, p-hydroxybenzoic acid, methyl p-hydroxybenzoate, methyl p-aminobenzoic acid, o-hydroxybenzoate, ethyl p-hydroxybenzoate, o-hydroxybenzoic acid, hexyl p-hydroxybenzoate, and combinations of any two or more thereof; and the second component is selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, decanal, glutaraldehyde, terephthaldehyde, hexamethylenetetramine, and combinations of any two or more thereof.
 24. A process according to claim 2 wherein said crosslinking agent comprises two components in which the first component is selected from the group consisting of phenol, hydroquinone, resorcinol, catechol, p-aminosalicylic acid, furfuryl alcohol, phenyl acetate, phenyl propionate, phenyl butyrate, salicylic acid, phenyl salicylate, aspirin, p-hydroxybenzoic acid, methyl p-hydroxybenzoate, methyl p-aminobenzoic acid, o-hydroxybenzoate, ethyl p-hydroxybenzoate, o-hydroxybenzoic acid, hexyl p-hydroxybenzoate, and combinations of any two or more thereof; and the second component is selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, decanal, glutaraldehyde, terephthaldehyde, hexamethylenetetramine, and combinations of any two or more thereof.
 25. A process according to claim 7 wherein said crosslinking agent comprises two components in which the first component is selected from the group consisting of phenol, hydroquinone, resorcinol, catechol, p-aminosalicylic acid, furfuryl alcohol, phenyl acetate, phenyl propionate, phenyl butyrate, salicylic acid, phenyl salicylate, aspirin, p-hydroxybenzoic acid, methyl p-hydroxybenzoate, methyl p-aminobenzoic acid, o-hydroxybenzoate, ethyl p-hydroxybenzoate, o-hydroxybenzoic acid, hexyl p-hydroxybenzoate, and combinations of any two or more thereof; and the second component is selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, decanal, glutaraldehyde, terephthaldehyde, hexamethylenetetramine, and combinations of any two or more thereof.
 26. A process according to claim 1 wherein said liquid is a produced brine.
 27. A process according to claim 22 wherein said liquid is a produced brine.
 28. A process according to claim 25 wherein said liquid is a produced brine.
 29. A process comprising introducing into a subterranean formation a gelling compositoin which comprises a water-soluble polymer, a crosslinking agent, and a liquid whereinsaid polymer comprises repeat units derived from at least one nitrogen-containing olefinic monomer and at least one olefinic comonomer; said nitrogen-containing olefinic monomer is selected from the group consisting of ##STR13## and combinations of any two or more thereof; said olefinic comonomer is selected from the group consisting of R₁ --C(R₁)═C(R₁)--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --Z, R₁ --C(R₁)═C(R₁)--Y--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --N(R₂)--Y--R₂, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --G--Y--Z, R₁ C(R₁)═C(R₁)--(C═O)_(m) --G--Y--W, R₁ --C(R₁)═C(R₁)--(C═O)_(m) --Y--Z; R₁ and R₂ are each independently selected from the group consisting of hydrogen, alkyl radical, aryl radical, aralkyl radical, alkaryl radical, and combinations of any two or more thereof wherein each radical contains 1 to about 30 carbon atoms; M is a substituted or unsubstituted morpholine group; each Y is independently selected from the group consisting of alkylene radical, phenylene group, imidazolium group, naphthylene group, biphenylene group, and combinations of any two or more thereof; Ar is an arylene group; G is N(R₁) or O; Z has the formula selected from the group consisting of N(R₂)(R₂), N⁺ (R₂)(R₂)(R₂)X⁻, and combinations thereof wherein X is an anion selected from the group consisting of halide, sulfate, phosphate, nitrate, sulfonate, phosphonates, sulfinate, phosphinate, and combinations of any two or more thereof; each m is independently 0 or 1; W is an acid moiety selected from the group consisting of phosphinic acid, phosphonic acid, sulfinic acid, sulfonic acid, sulfuric acid, sulfurous acid, carboxylic acid, phosphoric acid, ammonium salt or alkali metal salt of any of these acids, and combinations of any two or more thereof; and said crosslinking agent is selected from the group consisting of mutiltivalent metal compounds, two-component crosslinking systems, and combinations of any two or more thereof in which the multivalent metal compound is selected from the group consisting of zirconium citrate, zirconium complex of hydroxyethyl glycine, ammonium zirconium fluoride, zirconium 2-ethylhexanoate, zirconium acetate, zirconium neodecanoate, zirconium acetylacetonate, tetrakis(triethanolamine)zirconate, zirconium carbonate, ammonium zirconium carbonate, zirconyl ammonium carbonate, zirconium lactate, titanium acetylacetonate, titanium ethylacetoacetate, titanium citrate, titanium triethanolamine, ammonium titanium lactate, aluminum citrate, chromium citrate, chromium acetate, chromium propionate, chromium malonate, and combinations of any two or more thereof; and the first component of the two-component system is selected from the group consisting of phenol, hydroquinone, resorcinol, catechol, p-aminosalicylic acid, furfuryl alcohol, phenyl acetate, phenyl propionate, phenyl butyrate, salicylic acid, phenyl salicylate, aspirin, p-hydroxybenzoic acid, methyl p-hydroxybenzoate, methyl p-aminobenzoic acid, o-hydroxybenzoate, ethyl p-hydroxybenzoate, o-hydroxybenzoic acid, hexyl p-hydroxybenzoate, and combinations of any two or more thereof, and the second component of the two-component system is selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, decanal, glutaraldehyde, terephthaldehyde, hexamethylenetetramine, and combinations of any two or more thereof.
 30. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is selected from the group consisting of N-acryloyl morpholine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(3-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-ethyl piperazinium chloride, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinyl imidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinyl imidazolium chloride, N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, and combinations of any two or more thereof.
 31. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is selected from the group consisting of N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N-acryloyl-N'-methyl-N'-(2-amino-2-oxoethyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(2-amino-2-oxoelhyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinylimidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinylimidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinylimidazolium chloride, and combinations of any two or more thereof.
 32. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is N-acryloyl-N'-methyl piperazine.
 33. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt.
 34. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride.
 35. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt.
 36. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride.
 37. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride.
 38. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propaneammonium inner salt.
 39. A process according to claim 29 wherein said nitrogen-containing olefinic monomer is N-acryloylmorpholine.
 40. A process according to claim 29 wherein said olefinic comonomer is selected from the group consisting of acrylamide, styrene sulfonic acid, salt of styrene sulfonic acid, N-methylacrylamide, N,N-dimethylacrylamide, acrylic acid, salt of acrylic acid, N-vinylpyrrolidone, methyl acrylate, methacrylate, vinyl sulfonic acid, salt of vinyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, salt of 2-acrylamido-2-methylpropanesulfonic acid, and combinations of any two or more thereof.
 41. A process according to claim 29 wherein said olefinic comonomer is acrylamide.
 42. A process according to claim 29 wherein the second component of said two-component system is hexamethylenetetramine.
 43. A process according to claim 31 wherein the second component of said two-component system is hexamethylenetetramine.
 44. A process comprising introducing into a subterranean formation a gelling composition which comprises a water-soluble polymer, a crosslinking agent, and a produced brine whereinsaid polymer comprises repeat units derived from at least one nitrogen-containing olefinic monomer and at least one olefinic comonomer; said nitrogen-containing olefinic monomer is selected from the group consisting of N-acryloyl morpholine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(3-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-ethyl piperazinium chloride, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(2-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinyl imidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinyl imidazolium chloride, N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propaneammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethaneammonium inner salt, and combinations of any two or more thereof; said olefinic comonomer is selected from the group consisting of acrylamide, styrene sulfonic acid, salt of styrene sulfonic acid, N-methylacrylamide, N,N-dimethylacrylamide, acrylic acid, salt of acrylic acid, N-vinylpyrrolidone, methyl acrylate, methacrylate, vinyl sulionic acid, salt of vinyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, salt of 2-acrylamido-2-methylpropanesulfonic acid, and combinations of any two or more thereof; and said crosslinking agent comprises two components in which the first component is selected from the group consisting of phenol, substituted phenols, aspirin, p-aminobenzoic acid, resorcinol, catechol, hydroquinone, furfuryl alcohol, R'ArO (C═O)_(m) R', HOAr (C═O)_(m) OR', HOArOH, R'OArOH, R'OArOR', and combinations of any two or more thereof wherein Ar is non-substituted or substituted arylene group; each R' can be the same or different and is each independently selected from the group corsisting of hydrogen, carboxylic group, a C₁ -C₆ alkyl, a phenyl group or combinations of any two or more thereof; and each m is independently 0 or 1; and the second component is selected from the group consisting of aldehydes, aldehyde-generating compounds, and combinations of any two or more thereof.
 45. A process according to claim 44 wherein said nitrogen-containing olefinic monomer is selected from the group consisting of N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoetliyl)-N'-vinyl imidazolium chloride; andsaid olefinic comonomer is acrylamide.
 46. A process accordin to claim 45 wherein said second component of said two-component system is hexamethylenetetramine.
 47. A process according to claim 46 wherein said liquid is a produced brine. 